fix(jqLite): ignore incompatible nodes on find()

[hsablonniere]

When a jqLite collection contains text nodes, find() does not work :-(

This fix ignores all nodes than can't do getElementsByTagName()

It seems a little bit faster than testing nodeType : http://jsperf.com/nodetype-vs-duck-typing

Closes #4120

[mary-poppins]

Thanks for the PR!

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Thanks again for your help!

[hsablonniere]

Is mary poppins supposed to check the boxes ? I signed the CLA for another commit and my commit message should follow the rules...

Let me know ;-)

[tbosch]

Landed in master as 1169b54.
Thanks for this nice PR: Good commit description and with a good test.

[hsablonniere]

Thanks Tobias ;-)